Microwave signature for gas sensing: 2005 to present

Abstract We present here the development and the implementation of a technique of gas detection involving a microwave transduction method. The use of low-cost sensors based on microstrip or coplanar structures, adapted to the microwaves domain, allows the sensitive materials deposition under various forms. The purpose of the study is to assess the interest of microwave transduction for gas detection. The choice of the sensitive materials concerns materials widely used in the field of gas sensing: the metal oxides (SnO2 and TiO2) as well as molecular materials like cobalt phthalocyanine (CoPc). In this article we shall apply to explain the principles of the microwave transduction before appr…

EXPERIMENTAL OBSERVATION OF THE INTERACTION BETWEEN A MICROSCOPIC CATHODE TIP AND ELECTRICAL ARC

Experimental approach of the interaction between a sub-microscopic cathode tip and the plasma

The interaction between electrical arc and cathode represents a crucial problem in the conception of arc jet thrusters, circuit breakers, and plasma torch or arc heaters. At the cathode surface, the current and energy transfers are controlled by the current emitting site (cathodic spot). Theories and experimental observations, at macroscopic and mesoscopic scale, deal with the erosion of the cathodic surface. Under micrometer range, theories refer to the arc root to describe the erosion of the surface. The works presented here propose an original method to evaluate the arc-cathode interaction at micrometric scale. A nanotechnology is used in order to control the roughness of the electrode s…

The multimodal detection as a tool for molecular material-based gas sensing

Abstract The adsorption of a target gas on a material induces a change in several physical characteristics, such as the dielectric constant, the work function or the conductivity. The use of different transducers sensitive to the variation of these parameters appears to be a relevant methodology worthy of investigation. In the field of sensors, molecular materials present interesting and potentially valuable features as sensing elements for real gas sensor applications. In this article, we review the different types of conductimetric transducers and also show how a molecular material-based microwave transducer can be used for gas sensing. Among conductimetric transducers, resistors have bee…

Microwave-based gas sensor with phthalocyanine film at room temperature

Abstract This work presents the development of a microwave gas sensor at room temperature. The design of the sensor includes a coplanar grounded wave guide where is deposited a molecular gas sensing material. In this study, the sensitive material is a thin layer of cobalt phthalocyanine (CoPc), sensitive to ammonia and toluene. Submitted to an electromagnetic incident wave in the microwave range, the sensor response is a reflected wave. In the presence of pollutant, the reflected wave shape is specific to the species concentrations. The results interpretation is led at each frequency by the evaluation of the reflected coefficient, which traduces the ratio between the reflected wave over the…

Development of gas sensors by microwave transduction with phthalocyanine film

International audience; This work presents a new transduction mode for gas sensing using a passive microwave circuit at room temperature. The design of the sensor includes a microstrip line where is deposited a thin molecular layer of cobalt phthalocyanine (CoPc). The material is sensitive to ammonia and toluene. Submitted to an electromagnetic incident wave in the microwave range, the sensor response is a reflected wave. In the presence of ammonia, the reflected wave is specific to the species concentration. The sensor response is the reflected wave over the incident wave ratio at each frequency traduced by the reflected coefficient. The study deals with the influence of molecular sensitiv…